1. Field of the Invention
This invention relates to a magnetic rotary seal and more particularly to a variable magnetic rotary seal which is for use in aircraft, aerospace, marine, pumps, blowers, automotive and bearing housings.
2. Description of the Prior Art
U.S. Pat. No. 2,843,403, entitled Rotary Seal, issued to Robert Stevenson on July 15, 1958, teaches a rotary seal which sealingly couples a housing to a shaft mechanism. The rotary seal includes a first member, a second member and a springless mechanism. The shaft extends through the housing. The first member is held against rotation relative to the housing. The first member has a first annular sealing surface in a first plane. The second member has a second annular sealing surface in a second plane. The first plane is parallel and adjacent to the second plane. The second annular sealing face fluidly engages with the first annular sealing surface. The second member is mounted on the shaft for rotation therewith. A soft "O" ring is disposed between the shaft and the first member in order to mount the soft "O" ring so that it is anchored to the shaft. The first member still has axial and rocking movement relative to the shaft for engagement and alignment of the faces. The springless mechanism secures the second member to the housing. The springless mechanism is disposed uniformly circularly about the axis is of the shaft and consists of a sealing ring and a mating ring. The mating ring has a plurality of recesses and a plurality of wall sleeves. Each recess has a bottom wall. Each wall sleeve is made out of a non-magnetic conducting material, such as lead or brass. The mating ring carries a plurality of equally spaced, separate cylindrical plugs. Each cylindrical plug is made out of a magnetized material, such as "Alnico." Each cylindrical plug is disposed in one of the plurality of wall sleeves. A wall sleeve must surround each cylindrical plug. Each recess frictionally receives one of the wall sleeves. The plurality of cylindrical plug magneticly attracts the sealing ring. The second member carries the sealing ring in order to draw the sealing faces together. The rotary seal prevents the escape of fluid under pressure from between the two relatively rotatable parts. If it is more convenient for manufacturing each recess may be made in the blank of the mating ring prior to the hardening process.
U.S. Pat. No. 2,913,289, entitled Ball Bearing Seal, issued to Robert Stevenson on Nov. 17, 1959, teaches a rotatable sleeve which is used in combination with a ball-bearing which has two ball races. One ball race is provided with a sealing surface. The rotatable sleeve is held against rotation relative to the other ball race. The rotatable seal has a sealing surface thereon projecting into sealing engagement with the first sealing surface. A ring type magnet is carried by the rotatable sleeve which cooperates magnetically with the ball bearing to axially urge the sealing surfaces into engagement. The first ball race is the inner ball race of the bearing. The seal has an "Alnico" mating ring with a carbon steel seal head. The seal pulls both parts together. Since the strength of the "Alnico" magnet is limited because of its low magnetic pull the length of the carbon face which is the major wear component is limited.
U.S. Pat. No. 3,080,170, entitled Seal Providing for Substantial Axial Movement issued to George E. Colby on Mar. 5, 1963, teaches an annular seal member which is used in a seal between a shaft and a housing. The shaft extends through the housing in which the shaft has axial movement relative to the housing of a predetermined distance. The annular sealing member is disposed in the housing. The annular sealing member surrounds the shaft and has an annular recess which extends radially from the shaft. An "O" ring is disposed in the recess and has a body circular in cross section engaging the shaft One half of the circumference of the cross section of the body of the "O" ring is greater than the predetermined distance of the axial movement of the parts. In order to prevent rolling of the "O" ring greater than 180 degrees, the recess has end walls which are fixed relative to each other between the "O" ring. The end walls are spaced in an axial dimension at least equal to one half of the circumference of the "O" ring body in order to prevent restriction of rolling of the "O" ring.
U.S. Pat. No. 3,050,319, entitled Radially Contacting Seal with Balancing Sleeve, issued to George E. Colby on Aug. 21, 1962, teaches a rotary seal which prevents the escape of fluid under pressure from between relatively rotatable parts. The rotary seal includes a housing, a shaft, a first member, and a second member. The shaft extends through the housing. The first member surrounds the shaft and has an annular sealing surface thereon in a single plane. An "O" ring between the first member and the housing anchoring the first member thereto against relative rotary movement. The second member has an annular sealing surface thereon in a single plane in fluid sealing engagement with the first annular sealing surface, an "O" ring between the second member and the shaft anchoring the second member thereto against relatively rotatable movement. One member is wholly a magnetized material and the other member includes a magnetically attracted material drawing the sealing faces together. The two members together are spaced at one of their ends for a limited axial movement together relative to the housing and the shaft and the members are also spaced from the parts along their circular surfaces sufficiently for individual rocking movement of the members about the "O" rings for alignment of the sealing faces. The members are unrestrained by any external influence and rotation of the shaft, even though its axis is at a slight angle to the axis of the housing will cause the members to align the sealing faces in a plane perpendicular to the shaft axis.
U.S. Pat. No. 3,708,177, entitled Magnetic Seal for a Rotary Shaft and Magnet Therefor, issued to Max Baermann on Jan. 2, 1973, teaches a magnetic seal which includes a cylindrical magnetic member for surrounding a rotary shaft. The rotary shaft projects through a housing. The cylindrical magnetic member includes an outer circumferential seal cooperating with the housing. A cylindrical magnetically attractive member also surrounds the rotary shaft and includes an inner circumferential seal cooperating with the rotary shaft. The magnetically attractive member rotates with the rotary shaft and a magnet is stationary with housing. A sealing member is interposed between the magnet and the magnetically attractive member. Magnetic attraction between the magnet and the magnetically attractive member draws the two members together to form a seal with the interposed sealing member. The magnet is molded of anisotopic ferrite permanent magnet material which is oriented in a radial direction during molding and is also radially magnetized.
U.S. Pat. No. 2,944,843, entitled Spring Loaded Seal, issued to George E. Colby on July 12, 1960, teaches a fluid seal device which effects a fluid tight sealing between two relatively rotatable members. A resilient mechanism urges the sealing faces on the members into sealing engagement. A magnet urges the members into sealing engagement. The magnet exerts a force sufficient to critically dampen the resilient mechanism and less than the force required to form a fluid tight seal between the faces.